Noise Reduction in an Interior Permanent Magnet Synchronous Motor through Structural Modifications

In this paper, we identify the noise source of an interior permanent magnet synchronous motor (IPMSM) for servo systems and reduce the noise level of the motor through structural modifications. To identify the main noise source, noise and vibration signals were measured at various motor speeds and installation positions, and the frequency spectra of these signals were analyzed. From the experimental analysis, axial clashing caused by the precession of the brake disk in the gap between the brake plates was identified as the major source of noise. To reduce the noise, we propose structural modifications, including altering the brake system to incorporate an O-ring, enlarging the shaft diameter, and increasing the space between bearings. A prototype with these modifications was tested, resulting in a noise reduction of up to 16.0 dB(A).